beginning-iphone-3-development.markdown

Beginning iPhone 3 Development: Exploring the iPhone SDK

by David Mark and Jeff LaMarche

I, Michael Parker, own this book and took these notes to further my own learning. If you enjoy these notes, please purchase the book!

Chapter 1: Welcome to the Jungle

pg 7: The iPhone doesn't write memory to a swap file, so usually only half the memory of a 128MB of 256MB device is left for you to use.

Chapter 2: Appeasing the Tiki Gods

• pg 21: In IB, File's Owner is what loaded the nib file from disk and so “owns” the nib file; first responder is the current object with which the user is interacting.
• pg 23: UIKit on Cocoa Touch is like AppKit on Cocoa; the Foundation framework classes are shared between them, however.
• pg 26: Icons must be 57x57 PNG images, which should always be used as they are actually optimized by Xcode at build time.
• pg 29: Delete the iPhone Simulator folder from ~/Library/Application Support to clear out old applications from the simulator's home screen.

Chapter 3: Handling Basic Interaction

• pg 35: Put the IBOutlet keyword in the property declaration; putting it before the instance variable declaration will fail if you rename the variable using the @synthesize directive.
• pg 43: Use autorelease only when you absolutely have to, and not to simply save a line or two of code.
• pg 44: Every iPhone application has one UIApplication instance, which will call methods on its delegate at well-defined points during execution.
• pg 55: When associating buttons with actions, do so from the connections inspector window for the button.

Chapter 4: More User Interface Fun

• pg 60: Controls are active, static (or inactive), or passive, which simply hold on to a value until ready for processing later.
• pg 64: Holding the option key when resizing a view reveals the distance from each edge; selecting Show Bounds Rectangles in the Layout menu reveals the true size of any view.
• pg 66: For performance: use an Alpha of 1; under Drawing uncheck Clear Context Before Drawing and Subviews; and don't select a Mode that resizes an image.
• pg 68: The text base guideline ensures that a label and the text entered into a text field are aligned on the bottom.
• pg 74: The container view can be changed from a UIView to the UIControl subclass to capture background taps and dismiss keyboards and number pads.
• pg 90: Use an action sheet if a choice must be made; to simply notify the user without giving a choice, use an alert sheet.
• pg 93: Most buttons on the iPhone are drawn using images; Apple provides many in the UICatalog program, which you can redistribute with your application.
• pg 94: Controls are either normal, highlighted, disabled, or selected, which is similar to highlighted but can persist even when the user is no longer directly using that control.
• pg 95: When a view gets unloaded, its viewDidUnload method should assign nil to its properties so that their retain counts reach zero and memory is freed.

Chapter 6: Multiview Applications

• pg 119: A UIView or one if its subclasses that has a corresponding view controller is called a content view, because it's a container for application content.
• pg 123: The root controller is loaded when the application loads and is responsible for displaying the appropriate content view.
• pg 127: The application delegate, in application:didFinishLaunchingWithOptions, can add the view of the root controller to the application window.
• pg 131: Toolbar buttons support only a single target action at the moment equivalent to a Touch Up event on other iPhone controls.
• pg 137: The view output of a controller must be reconnected with the view in the nib if the underlying class of the file's owner is changed.
• pg 142: Caching an animation makes it smoother by taking a snapshot of the view when it begins, but you can't change the appearance of the view during the animation.

Chapter 7: Tab Bars and Pickers

• pg 148: While a picker gets its data from a delegate, its datasource specifies how many components it has and how many rows per component.
• pg 153: Clicking on a tab in IB will first select the associated view controller; clicking again will selects the tab bar item itself.
• pg 161: NSInteger is defined as either int or long; the compiler automatically chooses whichever size is best for the platform you're compiling for.
• pg 162: Store data in property lists when you can; this will allow you to edit data without recompiling, and make internationalization easier.
• pg 175: A bundle is a special folder whose contents follow a specific structure; you'll typically use it to access items in your Resources folder.
• pg 179: Interface Builder will let you assign any font to a label, but the iPhone has a very limited selection of fonts.
• pg 188: Method performSelector:withObject:afterDelay is available on all objects and allows calling a method sometime in the future.
• pg 190: To add a framework, right-click on the Frameworks folder under the Groups & Files pane, and select Existing Frameworks from the Add submenu.

Chapter 8: Introduction to Table Views

• pg 195: Grouped table views have rows grouped in rectangles with rounded corners; plain tables have no rounded rectangles.
• pg 196: The iPhone HIG explicitly states that grouped tables should not provide indexes.
• pg 200: Always try to reuse a cell by calling dequeueReusableCellWithIdentifier, ensuring that you guard against nil values.
• pg 203: UIImage uses a caching mechanism based on the filename, so calling it repeatedly will return a cached instance.
• pg 205: Unlike pickers, in a table the delegate configures the appearance of the table and handles certain interactions; it doesn't provide data.
• pg 210: To customize table cells, either add subviews to instances of that class, or subclass it.
• pg 240: Actions are executed a tiny bit sooner in tableView:willSelectRowAtIndex versus tableView:didSelectRowAtIndex.
• pg 241: Implement searchBar:textDidChange to show a live search, but test extensively on hardware first to ensure good performance.
• pg 242: The index will overlap with the search bar unless you explicitly disable indexing while the search bar has focus.
• pg 243: Putting a search bar above the table view consumes valuable screen real estate; instead, add a search icon to the index for easy access.

Chapter 9: Navigation Controllers and Table Views

• pg 249: A detail disclosure button says that selecting the row will reveal detailed information about the row, while tapping the row can perform another action.
• pg 253: Subclassing UITableViewController will create a table view automatically, without the need for a nib file.
• pg 254: The root controller is the first controller loaded by the application; UINavigationController has a root controller which is the bottom of the navigation stack.
• pg 262: If passing data to a subcontroller, assign to temporary variables that are copied to outlets in viewWillAppear; outlets are nil until its nib file loads and viewDidLoad is called.
• pg 284: If allowing the user to rearrange items, don't flush data in viewDidUnload, or the new arrangement will be lost when returning.
• pg 287: To use the move control in the simulator, you must select one of its pixels with your single-pixel hot-spot cursor; it's easier with fat fingers on a real device.
• pg 294: If you implement edit mode to allow deletes, horizontal swipes across a row will also reveal the Delete button.
• pg 300: If using a table view to implement a detail view without any nib file, just recreate the child controller each time; attempting reuse can introduce complexities.
• pg 302: If a text field being edited scrolls off the screen, its updated value may be lost; implementing UITextFieldDelegate allows you to save whenever an edit is made.
• pg 309: Use UIBarButtonItemStyleDone for buttons that users tap when they are happy with their changes and ready to leave the view.
• pg 316: If a view is composed entirely of text fields, have the keyboard's return button move on to the next text field.

Chapter 10: Application Settings and User Defaults

• pg 322: The settings application is a common UI for the User Defaults mechanism; immersive apps should provide their own preferences view as well.
• pg 332: The Values array of PSMultiValueSpecifier and the TrueValue and FalseValue of PSToggleSwitchIdentifier can store any type.
• pg 333: The DefaultValue of PSMultiValueSpecifier or PSToggleSwitchIdentifier must specify a value in Values, or in TrueValue or FalseValue.
• pg 336: The settings bundle can't read from your application's sandbox, so images required by a bundle must exist in the bundle.

Chapter 11: Basic Data Persistence

• pg 352: Custom objects cannot be serialized into property lists, and neither can other delivered classes from Cocoa Touch.
• pg 359: Any class written to hold data should implement NSCoding and support archiving; also implement NSCopying for good measure.
• pg 361: Copied objects are implicitly retained and should therefore be released or autoreleased in the code that called copy or copyWithZone.
• pg 368: Aggregations in SQLite3 is several orders of magnitude faster than loading all objects into memory and doing it yourself.
• pg 370: A NSString is converted to a C-string using the UTF8String method; it is created from one using initWithUTF8String.
• pg 371: Confusingly, either sqlite3_step returns the next result from a query, or commits an update.
• pg 381: An entity is a description of an object you write in XCode, while managed objects are the concrete instances of the entity created at runtime.
• pg 382: A fetched property is where an attribute of an entity is not loaded until the attribute is actually needed.
• pg 383: The managed object context, which intermediates access to the persistent store, registers all changes with the undo manager up until the last time a save was performed.
• pg 385: New managed objects and retrieved managed objects are not saved until the managed object context retrieves a save message.

Chapter 13: Taps, Touches, and Gestures

• pg 438: Taps are only kept track of when one finger is used; if it detects multiple touches, the tap count is reset to one.
• pg 439: Events are passed to a view, then its controller, and then the superview, and then its controller, all the way up to the UIApplication instance if not consumed.
• pg 440: If a gesture affects more than the object being touched, the event handling code belongs in the view controller's class; otherwise, it can go in the view itself.
• pg 441: All touches are passed to an event handler; it is up to that handler to filter touches outside of its view or desired scope.
• pg 449: Beware that touches are in an NSSet and can be reordered across calls, and one finger may touch before others in a multi-finger swipe, so touchesBegan:withEvent: has just one touch.
• pg 455: Delay actions performed on some number of taps by 0.4 seconds; if another tap occurs, incrementing the tap count, you can still cancel the previous action and schedule a different one.
• pg 464: Test your custom gesture to ensure that it does not conflict with other gestures in your application.

Chapter 14: Finding Your Way Around With Core Location

• pg 465: Choose the minimum accuracy level needed and don't poll for location any more than absolutely necessary to reduce battery drain.
• pg 468: A negative value of horizontalAccuracy means the latitude and longitude cannot be relied on; a negative value of verticalAccuracy menas the altitude cannot be relied on.

Chapter 15: Whee! Accelerometer!

• pg 478: The accelerometer increases y with upward force, which is what OpenGL ES expects, but must be translated when using Quartz 2D.
• pg 479: The accelerometer supports 100 updates per second second, although that throughput and the uniformity of time between updates are not guaranteed.
• pg 480: Light shakes register at 1.5 gs, and strong shakes at 2.0 gs, while the accelerometer can't seem to register anything beyond 2.3 gs.
• pg 482: Normally, use motionBegan:withEvent and motionEnded:withEvent; only use UIAccelerometer directly if you need more control over the shake gesture.
• pg 494: The synthesize directive will not overwrite any accessor or mutator methods you write; it will simply provide the ones you don't.
• pg 494: Nib files contain archived objects, so any additional initialization of those objects must be performed in initWithCoder.

Chapter 16: iPhone Camera and Photo Library

• pg 499: Even though applications are sandboxed, your application still has access to the image library by way of an image picker.
• pg 503: If an image returned to your delegate comes from the camera, it is not stored in the photo library, and so your application must save it if needed.
• pg 504: Since UIImagePickerController subclasses UINavigationController, you must conform to both protocols UIImagePickerControllerDelegate and UINavigationControllerDelegate.
• pg 508: All iPhone OS devices support a photo library, which you can resort to if the device does not have a camera.

Chapter 17: Application Internationalization

• pg 512: If an application can't find a language project that matches the language/region pair or just the language, it uses the resources from the development base language.
• pg 515: The NSLocalizedString macro is used with genstrings to create string files; at runtime, the macro looks for the best strings file to use, or simply returns the first argument as the string.
• pg 522: When dealing with locales, language codes are lowercase, and the optional country codes that follow are uppercase.
• pg 526: When adding Localizable.strings to your project, change the encoding to Unicode (UTF-16) when prompted, and then localize the file.